Typically, an array of plated through-hole vias is drilled and plated to thermally transfer heat from one side of the PCB to the other side of the PCB in a z-axis direction. However, it is time consuming and often unreliable to plate copper to a thickness greater than a small percentage of the via hole. For this reason, thermally conductive epoxy fillers are typically placed in the via holes. Nonetheless, thermally conductive epoxy filler typically makes a negligible contribution to the overall thermal conductivity because its thermal conductivity is substantially less than copper. Filling the via holes with traditional solder not only has much lower thermal conductivity than a copper material, but also can flow out during subsequent thermal processing.